Electric switch



Dec. 9, 1924 B. A. BENSON ELECTRIC SWITCH Filed March 29, 1924 Patented Dec. 9, 1924.

UNITED STATESA PATENT OFFICE.

BERNHART A. BENS ON, OF CHICAGO, ILLINOIS, ASSIGNOR TO -ECDBIIIUN'DS @c JO'NES CORPORATION, -A CORPORATION F NEW YORK.

ELECTRIC, swrfron'.

Application filed March 29, 1.924. Serial No. 702,776.

a full, clear, and exact description of the invention, such as will enable others skilled in the art to whichl it appertain's to make and use the same.

My invention relates to electric switches of the pull orpush type. Generally speaking, the objects of myinvention include the providing of a simple, cheaply and easily manufactured switch which will afford selfcleaning contact surfaces, which will permit a considerable continued movement of the switching member in its circuit-closing direction after the circuit is closed, and which will have this switching member spring-retracted so as to open the circuit automatically when the actuating pull or pressure is relaxed. Furthermore, my invention provides a switch construction for this general purpose which will require a minimum of fastening elements.

More particularly, my invention provides a switch construction in which the circuit is closed by the direct contacting of the arms of a resilient switching member with the binding posts of the switch, and one in which these arms are so formed and dis-f posed as to be bent towards each other by engagementwith the wire terminals so as to afford a wiping or self-cleaning contact and so as to maintain this contact during aconsiderable prolonged movement of the switching member. It also provides a novel and simple mounting for the switching member, an effective connection between the circuitclosing portion of this member and a reciprocating plunger, and a cheaply constructed casing assembly which will requirel no auxiliary fastening elements. Still further and also more detailed objects of my invention will appear from the following specification and from the accompanying drawings, in

whichl Fig. l is aperspective bottomv view of a switch embodying my invention and particp ularly adapted for use as a pull switch in connection with the vstop-light signal of a vehicle.

, Fig. 2 is an enlarged top view of the same switch with they top plate removed and with the switching member in its normal, springretracted position.

Fig. 3 is a correspondingly enlarged horizontal section taken along the line 3-3 of Fig. 4.

Fig. 4 is a central, vertical and longitudifnal section through the switch, namely a section along the lined-4 of Fig. 2.

Fig. 5 is a transverse vertical section taken through the binding posts or wire terminals of the switch, or along the line 5-5 of Fig. 2.

' Fig. 6 is a sectionthrough a portion of the plunger of the switch and through the washer 20 as originally formed, showing a step in the securing of this washer to the plunger.

Fig. 7 is a similar section/showing this washer as flattened and forced into the formed upwards from the bottom 1, while also having a pair of ends 3 formed upwards and each continued by an end flange t having its top flush with the upper edges of the sides 2. i

Extending through the bottom, 1 of the casing are a pair of binding posts 6 each of which is threaded to receive a screw 7 for securing the end of one of the circuit wires 8 to the same, so that the posts 6 form the effective wireterminals of the switch. Ea'ch of the posts 6 has a shank portion extending through a perforation in the bottom l of the switch, the perforation in each case being considerably larger than the shank of the post, and the two posts also serve for clamping a pair of insulatingblocks 9 and 10 respectively against the lower and upper faces? of the bottom of the casing. For this latter purpose, each post desirably has a contact portion of larger diameter than lts shank portion exposed within the casing and beyoud the inner insulating block 10, thereby affording a shoulder at the juncture of this larger diametered contact port1on with the shank of the post` while the outer end of the .post is flared over the exposed face of the insulating block 9 after the manner shown in Fig. 5. Thus arranged, the -two posts clamp these insulating blocks tightly to the bottom of the switch casing, thereby preventing the two insulating blocks as well as inner insulating block 10 of a size closely approximating the interior width of the casing and -desirably have this inner block abut against the nearer end wall 3 of the casing, so as to aid in resisting any sliding tendency which might be'due to the thrust of the circuit-closing member.

Extending slidably through alined bores in the ends 3 of the casing* is a plunger 11 which forms the actuating. member of the switch and which desirably has a head 12 adapted te engage one of the said end walls so as to limit the movement of this stem in the circuit-closing direction. When my appliance is to be used as a pull switch, l desirably provide the other end of the reciprocating plunger 1l with a perforation 13 for receiving a hook end of a spiral end 14 or other connecting link through which the operating pull is transmitted to the sliding plunger of the switch.

The sliding plunger 11 extends through a perforation in an insulating block 15 and the plunger desirably has a larger diametered portion disposed between that block and the head 12 so as to aord a shoulder against which the block 15 is normally pressed by a spring 16. This spring bears r at its other end against the" opposite head 3 of the switch casing, thereby continuously tending to move both the said insu lating block andthe plunger in one direction, namely that in which it opens the circuit. s

The insulating block 15 desirably is of such a size as to have only a light rubbing engagement with the bottdm 1 of the switch casing. whereby this bottom serves to prevent the rectangular block from rocking .about the plunger asA an axis. Secured to the insulatingblock 15 is a1 circuit-closing member which desirably'consists of a fork formed 'of bronze or other resilient metal and having a back portion 17 secured flatwise to the insulator 15 by a-rivetl 18. Each arm 19 of the said forkhas its free end curved towards that of the other arm and the fork member is so formed that its resiliencyv will normally spread the bent portions of the posts from moving with respect to thev casing. Furthermtire, l desirably make the the free ends of its arm a greater distance vapart than the distance between thetwo binding posts 6 which form the terminals of the switch. Moreover, these arm tips are i When the plunger is moved in a direction which is towards the left in Figs. 2 and 4. either by pressing the head 12 or by pulling on the link 14. the bent tips of the fork arms 19 respectively. engage the two posts 6 lafter a predetermined movement of the plunger in the said direction, as shown in dotted lines in Fig. 3. Then a continued movement of the plunger in the same direction will cause the curved Yisurfaces of the posts 6 and the bent tips of the said arms to cooperate i-n affording a cam action so as to force the arms towards each other. Consequently, these arms will continue to contact respectively with the two posts during a considerable range of movement of the actuating plunger as indicated by the full lines in Fig. 3, which lines show the plunger as stopped at the limit of its circuit-closing movement by the engagement of the 'head 12 of the plunger with the adjacent end wall 3 of the casing. Owing to the wiping action thus secured, the switch of my invention is self-cleaning and will automatically clear itself of any dust which may have settled on the terminal posts .or on the resilient switching member. So also, the contacting of the arms of the switching fork with the said terminals during a prolonged movement of the switching member adapts my switch to purposes where the extent of movement of the actuating member may vary considerably, as for example .in the stop-light switches of automobiles which are commonly connected to the brake levers for their actuation. To prevent the plunger from being withdrawn from the casing towards this head4 end, l provide this with an enlargement adapted to engage the inner face of the casing end which is adjacent to the head of the plunger, as shown by the head 2O of Fig.'4.

It Will be obvious from the above that the switch of my invention is exceedingly simple and inexpensive in construction, that it re` quires very few fastening elements in its construction and that the contact arrange- `ment permits the resiliency of the forked switching element to compensate for any irregularities in the exact size or assembly of the parts. Moreover, since this forked met-al element is entirely disconnected from the circuitwhen in its normal retracted position, it is immaterial whether or not the rivet 8 touches the adjacent end wall of the casing at that time, or whether it is held away from lthe casing by he linterposing ofthe bead 20 between thai wall and theinsulatl ing block 8 of the switching member.

However, while have'illustrated and described the switch of my invention in an embodiment including numerous highlyA desirable` details of construction and arrangement, I do not Wish to be limited to these, as. man v changes might obviously be made 10 Without departing either from the spirit of my invention or claims.

For example, I am here snowing the plunfrom the appended ger or actuating element of the switch as provided With a bead which limits the novements of the insulator along the plunger J ond umll ofthe switch casing to limit the in one direction and which also engages one movement of the plunger in the same direc- 20 tion. (To permit a ready assembling o-f head of the plunger in the assembled switch,

and successively through the washer 20, thev insulator 15 and the spring. l then force the spring away from the insulator and Hatten the washer so as to cause it to enter the groove in the washer to the plunger as shown in Fig.

`i and causing this effectively to form a bead on the plunger. I`

laterally projecting also desirably increase the diameter of the plunger in the portion between this .groove and the head`of the plunger,s0 as to afford agreater thrust bearingagainstlthe washer in the directionv in which the thrust is exerted during the "circuit-closing movement of ,the plunger.

I claim as my invention 1. An electric switch comprising a casing, a reciprocable plunger mounted therein, a

pair of wire terminals disposed at opposite the plunger, thereby -anchoringv washerfastened to the plunger and disposed Vbetween the insulator and a wall of the casing and affording both ofthe said limiting means. l

A switch as .pei-claim 1, in which the plunger has a peripheral groove disposed between the insulator and a wall of the casing, in combination with a Washer having its radially inner portion disposed in the said groove, the Washer affording both of the said movement limiting means.

4. In an electric switch, a casing having a 'pair of end walls each provided with a perforation, a plunger extending through the said 'perforations and having an enlargement normally engaging the inner face of one of-'the said end walls to limit the movementof the plunger in one direction, an insulator mounted on the plunger, av spring continuously pressing the insulator against the said enlargement and thereby holding the enlargement against the said one of the -end walls and resisting a movement of the plunger in the opposite direction, a contact memberion the insulator, and aA circuit terminal mounted in the casing and engaged by the contact member when the plunger and the insulator are moved in the last named direction, the lunger having a head disposed `outside t e casing and adapted to engage the said one end wall to limit the movement of the plunger in the direction in which it causes the contact member to engage the circuit terminal.

5. In an electric Switch, a casing having a pair of end walls each provided with a perforation, a plunger extending through the said perforations and having an er largement normally engaging the inner face of one of the said end walls tolimit the movement of 4the plunger in one direction, y an "insulator mounted on the plunger, a spring sides ofthe plunger, an insulator disposedi tin the casing and having the plungerf extending through the same, the plunger having means engaged -by the casing to limit the movement of the plunger in one direction and also having meansl engaged by the '1nsulator to limit the movement of the insulator along the plunger in the same direction, spring ,means interposed between the insulator and the casing to urge the insulator in the said direction, and a contact member mounted on the insulator and adapted to contact with both wire terminals when the insulator is moved in the opposite direction against the resistance of the spring.

2. A switch as per claim 1, including a continuously pressing the insulator against the said enlargement and thereby holding the enlargement against the said one of the end walls and resisting-a movement of the plunger in the opposite direction, a contact member on the insulator, and a circuit terminal mounted in the vcasing and engaged by the contact member when the plunger and the insulator are moved in the last named direction, the insulator having a wall slidably engaging a wall of the Casin to prevent the insulator from rotating a out the plunger.

6. n an Velectric switch,a casing havinga pair of end walls each provided with a perforation, a plunger extending through the said perforations and having an enlargement normally engaging the inner face of one of the said end walls to limit the movement of the plunger in one direction, an insulator slidably mounted on plunger, a spring continuously pressing the insulator against the said enlargement and the thcreby holding the enlargement against the said one of' the end walls and resisting a movement of the plunger inthe opposite di-l rection, a contact member mounted on the insulator, land a pair of relatlvely Insulated l circuit terminals mounted in .the casing andA an .insulator mounted von the plunger, a.

` spring continuously pressing the insulator against the said enlargementand thereby holding the enlargement against the said one of the end walls and resisting a movement of the plunger in 4'the opposite direction, a

contact member mounted on the insulator,

a'nd a pair of relatively insulated circuit terminals mounted in the casing and both engaged by the contact member when the plunger and the insulator are moved in the last named'direction against the resistance of the spring, the contact member having a pair of arms extending in the said one dif a casing having' 4'posed in the path of the said Luana? rection, the arms having their free end portions bowed toward each other and having the bends of their said bowed `portions normally termin N l 8. An electric switch comprising a casing, a plunger extending slidably through the casing, an insulatorcarried b the plunger, a resilient and substantial y U- shaped'contact .member having its back fastened to the insulator and having arms extending in the same general direction with the plunger and bowed towards eachother, a pair of circuit terminals respectively disarms and spaced so as to flex the arms toward each other when the plunger is moved so as to carry the insulator and the contact member towardthe circuit `terminals, a spring continuously urging the plunger in the opposite direction,

and means for limiting the movement of,

-the plunger by the spring.

9. Anelectricswitch as per claim 8, in which the insulator has a perforation through which the plunger extends and has a portion slidably engaging a wall of the casin to' prevent the insulator from rotating a out the lunger.

Signed at C icago, Illinois, March 26th,

BERNHART A. BENSON.

spaced farther apart than 'the circuity a s 

